Breaking the Breeding Cycle – War on Fleas

Killing real live fleas, whether with insecticide or fingernail, gives many immediate satisfaction; with teeth clenched, it feels like a significant victory. The flea, however, often carries to their grave the satisfaction of knowing hundreds of their offspring will live on. Pet owners need to realise they’re not fighting individuals,  they’re fighting the reproductive capacity of the colony. While the lunge for a quick-fix, knock-down insecticide has it’s place, seeing the broader carpeted ecosystem stretching out before him, the owner with a more strategic vision will win..


Flea Breeding Cycle Facts

  1. Eggs are produced by adult females at a rate of up to 40 a day, and represent about 50% of the total population.
  2. Eggs are hard for most insecticides, including bombs, to penetrate and kill.
  3. Eggs, the tiny caterpillar-like larvae that hatch, and pupae, represent 95% of the total flea population, and are distributed around the skirtings, in cracks, in bedding and lounges, in gardens, at beaches and parks.
  4. Pupae can lay dormant for 6-9 months until warmth (>21c), humidity (>70%), and vibration triggers hatching.
  5. After larvae pupate, the emergent baby fleas must feed on blood within a week or THEY WILL DIE!

For more detail see War on fleas – know the enemy, choose a weapon.


Options for breaking the breeding cycle:

1. Sterilizing eggs

Lufenuron is the active in Program® for cats, and Sentinel Spectrum®, a monthly pill given to dogs, which prevents heart and intestinal worms, and also renders fleas infertile when they feed on blood. They produce eggs, but they never hatch. It’s safe and easy to use, and involves no insecticides, so popular amongst those concerned about chemical residues.

In late summer, about 25% of users complain these products doesn’t seem to be working. How could this be if fleas cant breed? If you live in an apartment, or your pet shares no part of their territory with other animals,  lufenuronmay completely eradicate your flea problem. Most animals, however, share some of their environment with other animals. This could be a cat that secretly enters your yard late at night, depositing a few fertile eggs, or those left behind when a friend’s flea-ridden dog comes over to play.

The good news is that when these eggs hatch into adult fleas, or when your cat or dogs pick up hitchhiker fleas at the beach or park, they will be quickly rendered infertile after drinking the lufenuronlaced blood of your pet.  Given lufenuron is not going to kill them, these fleas will happily feed, biting and irritating your dog, until they die of old age. These are the fleas that owners commonly view as product failure. Adding an insecticide, that kills adults, will swiftly eliminate the problem as there is never an accumulated egg bank.

So, in summary, when it comes to fleas: lufenuron may cure, usually helps, but needs to be given ALL year round, to ALL animals. This may make this product cost inhibitive for some pet owners. If your mates are always coming round with their flea-bags, or your dog  or cat hangs-out at the neighbour’s place all day, Sentinel® may be an expensive cripple that needs to be constantly propped up with other products.  If you find it’s not working well, it may be more cost effective to ditch it, and strategically spend the money on upping the hard-core adult killers.

Methoprene is an insect growth regulator (IGR) that, if applied to adults or larvae, disrupts the reproductive cycle. It’s so non-toxic the WHO recommends it’s use as an additive to inhibit mosquito larvae in drinking water. It’s in Frontline Plus®, some bombs, or can be sprayed around your house by licensed pest controllers..

lab glassware


2. Killing babies with environmental control:

95% of your flea population are babies (larvae, eggs, and pupae),  scattered around the house and garden, mostly where the animals lay and hang-out.  Like us, they love sand, bedding and lounges, and warmth but not sun. Regular vacuuming of floors, rugs and lounges removes many larvae, eggs and pupae.  Hot washing or spraying bedding and rugs will also help.

Carpet is a like a huge, synthetic, amazonian habitat designed specifically to nurture, protect and feed the dust mite and flea. If you can afford it, pull it up, it’s toxic; if not, steam cleaning kills babies.

The trouble with environmental control using chemicals (insecticide sprays and bombs) is the unwanted toxic collateral damage – overspray – inhaled, on surfaces, and near the vege patch. Poorly targeted insecticides will also kill insects that eat baby fleas such as ants. Insecticides are more strategically applied to the animal or bedding.  Application of borate salts to soils, sand, and surfaces kills larvae, and barricading off potential flea habitat, such as under the house, may be helpful.


3. Starving teens with strategic control:

Fleas in the pupal stage will not hatch until there is sufficient warmth, humidity and vibration: a signal a host is nearby. Yes, just like in Aliens. Once hatched they must feed on blood within a week or they will die. After feeding they can survive for many more weeks.

If you are moving into a vacant house in which previous tenants kept a couple of flea infested animals, there may be a fleabank of a few million dormant pupae laying in wait, ready to ambush. Allowing a gap of  a couple of summer months vacancy, before your pets move in, will allow pupae to hatch and then die of starvation, and may save you a lot of money and pet-stress. Even better, enter and stomp around: vibrations will trigger more hatching.

If you have a friend with multiple dogs, who is always complaining about their flea problems, discourage them from bringing their dog to your house and don’t take your dog to theirs. If your dog has visited a known flea-nest, apply an adulticide on return..

Having a husband with Parkinsons, one cat owner described her reluctance to use insecticides and solution to a severe flea outbreak. The two cats were temporarily relocated to a double garage: a space they  were usually denied access, so free of fleas. The owner applied a spot-on treatment on admission to the quarantine ward. Over the following 6 weeks of summer, the vibrations of human activity in the house stimulated the egg bank to hatch, then die of starvation. The cats returned form their holiday with the cars, to find a decimated flea population. Total cost: $26 for the 2 spot-on treatments, and transient grief from 2 grumpy cats..


  • Taking some steps to control the 95% of the flea population that are immature, in the environment, will save time and money. This may be as minimal as extra vacuuming, or may extend to borate, bombs and Sentinel/Program.
  • If your dog or cat is allergic to fleas, and loses hair over their rump every year, then the gold standard for flea control is lufenuron, all year round, and top up insecticides over summer if required.
  • If you have multiple animals, or pets that share alot of common territory with other cats and dogs, lufenuron may be too expensive or a ineffectual, and money may be better spent on other types of flea control.
  • While not wanting to condemn your dog to social isolation, be discriminating on where, and with whom your pet socialises.
  • Clever use of flea free spaces, or triggering egg hatch when no pets are around, can save money and is chem-free.


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5 Responses to “Breaking the Breeding Cycle – War on Fleas”

  1. Seattle Pest Control says:

    I am so lucky I found your website. Thanks for expressing your feelings.

  2. sue chakos says:

    thanks Matt, great advise. Interesting about the bee’s!
    Is it ok if I add this page address to our dog tips page when we do an article on fleas. Sometimes it can be bamboozeling to be given advise while at the vets and much easier to absorb, if reading about it.

  3. Sam says:

    Thanks for the well-thought article. I am actually at work right now! So I need to go off without reading all I’d like. But, I put your blog on my yandex feed so that I can read more.

  4. Ben says:

    Matt, recent experience with a flea plague here in Wooyung would seem to point to the limitations of advantix in terms of maintaining efficacy on dogs that go to the beach daily. With my own dog and two others that he plays with and visits regularly, Advantix has had little to no effect at all on the fleas in the first week of application. I have subsequently opted for Comfortis which not surprisingly has worked a treat, in conjunction with flea bombing.

  5. matt says:

    thanks for that, Ben. I agree, the comments regarding product failure for tick preventatives are equally relevant for flea control. Sun, sand and surf has the potential to deplete your expensive spot on and see you cursing big pharma. always let them know, as they may compensate you in some way, especially if you convince them you have applied it correctly, and its not an issue of fleas hatching as quick as they are killed.

    good luck

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